Poplar shelterbelt degradation plant and soil carbon dataset
Description
This dataset comprises comprehensive measurements of carbon (C) and nitrogen (N) pools in plant tissues (foliar, litter, and roots) and soil fractions (rhizosphere and bulk soil) across a degradation gradient in poplar shelterbelts. This study was conducted at the Experimental Center of Desert Forestry, Chinese Academy of Forestry, in Dengkou County, Inner Mongolia Autonomous Region, northern China. Plant and soil samples were collected in July, 2025. Three poplar species (Populus popularis, Lombardy poplar, and Populus alba) were sampled at four degradation stages (undegraded, mildly degraded, moderately degraded, and severely degraded) corresponding to degradation levels 1–4. Both rhizosphere and bulk soil fractions were collected for each tree species–stage combination, with three biological replicates per treatment. Variables included: Soil carbon pools (rhizosphere and bulk soil): MBC – Microbial biomass carbon (mg/kg) SOC – Soil organic carbon (g/kg) POC – Particulate organic carbon (g/kg) EOC – Easily oxidizable organic carbon (g/kg) WSOC – Water-soluble organic carbon (mg/kg) MAOC – Mineral-associated organic carbon (g/kg) Plant tissue carbon and nitrogen (foliar, litter, and root): C and N concentrations (g/kg) and C/N ratios for each tissue type.
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Steps to reproduce
For each combination of poplar shelterbelt type and degradation stage, three 20 m × 20 m plots were established as spatial replicates, resulting in a total of 36 plots. Five representative trees with mean stand condition of each shelterbelt type were selected for plant sampling. Fully expanded leaves were collected from the four cardinal directions of the canopy of each selected tree, then pooled to form one composite leaf sample per plot. Litter was collected using a five-point sampling design within each plot. Recently fallen litter was collected after removing adhering soil, stones, and non-target plant residues, and was pooled into one composite litter sample per plot. Fine-root samples were collected concurrently with rhizosphere soil sampling. For bulk soil sampling, the litter layer was removed before collecting 0–10 cm mineral soil at five points within each plot. Sampling locations were selected to avoid the immediate vicinity of tree stems and areas with coarse roots. The five subsamples were thoroughly mixed to obtain one composite bulk soil sample per plot, resulting in 36 bulk soil samples. For rhizosphere soil sampling, soil blocks containing fine roots were carefully excavated from the root zones of five representative trees within each plot. Loosely adhering soil was gently shaken off, whereas soil remaining tightly attached to fine roots was defined as rhizosphere soil. This soil was collected using sterile brushes and pooled to form one composite rhizosphere-soil sample per plot, resulting in 36 rhizosphere soil samples. Leaf, litter, and fine-root samples were initially heated at 105 °C for 15 min and then oven-dried at 65 °C to constant weight. Dried samples were ground and passed through a 100-mesh sieve. Their carbon (C) and nitrogen (N) concentrations were determined using an elemental analyzer (Integra2 EA, Sercon Limited, UK). Soil organic carbon (SOC) content was measured by the potassium dichromate oxidation method. EOC was measured using the potassium permanganate (KMnO4) oxidation method with ultraviolet spectrophotometry (UV8000). Particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) were separated by sodium hexametaphosphate dispersion and wet sieving through a 53 μm sieve. The >53 μm and <53 μm fractions were defined as POC and MAOC, respectively. DOC was determined in unfumigated fresh soil following extraction with 0.5 M K₂SO₄ and measurement using an automated TOC–TN analyzer (TOC-VCPH, Shimadzu, Kyoto, Japan). MBC content was measured using the chloroform fumigation-extraction method with K₂SO₄ extraction .
Institutions
- Beijing Forestry UniversityBeijing, Beijing